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HPSDAP
High Penetration Shield Depleting Armour Piercing (abbreviated HPSDAP) was a type of projectile ammunition used by The Royal Allegiance and the UNSC. History Introduced in 2607 alongside the BR662-SHR Battle Rifle for which it had been developed, the round was soon adapted for other calibres and weapons. Though banned from the civilian market, the ammunition type was widely used throughout the Allegiance and the UNSC armed forces. Although the weapon it had been designed for was slowly phased out of service from 2700 onwards, production of the ammunution did not cease until well after the conclusion of the Swarm War. Usage The round was predominantly used for the weapon it was designed for, the BR662-SHR Battle Rifle. The weapon itself was a license-built, heavily modified version of the UNSC's highly successful and popular BR55HB SR Battle Rifle. It had superb range, shield depleting qualities, weight and armour-piercing ability. In use with other weapons the round was more successful in higher calibres, though was effective at longer ranges in carbines and SMGs. Some experimental antitank rounds of the HPSDAP type were created, with great success. Technical Details The explosive propellant was an advanced highly combustible material, which allowed for increased levels of chemical energy inside the casing, as the ammunition made use of advanced chemical with a very high energy to density ratio. This allowed for an increased explosive force and so a faster bullet velocity. The casing itself was also entirely combustible, adding to the velocity of the bullet. The casing when combusted did not contribute massively to the bullet's velocity but was enough to ensure exceptional bullet speeds and resulting in superior penetration and damage characteristics. This meant that above average bullet speeds were achieved despite the bullet's size. The bullet's core was made of tungsten carbide, which gave the bullet increased mass and meant it imparted much more kinetic energy upon impact with a target. The core was surrounded by a titanium carbide penetrator which guaranteed deep penetration. The bullet featured a depleted uranium tip, designed to hold its shape after impact with a target. The entire bullet was surrounded by a polymer, the primary function of this being to withstand the great pressure and heat of being expelled from the barrel. As a secondary function, it meant that during flight, the bullet acquired an electrical charge. The longer the bullet was in the air, the more charged it became. This was particularly useful against shielded targets, as the charged bullets would not only deplete the shield with kinetic energy but electrical too. This ability resulted in the round's designation as 'shield-depleting'. It was at its most effective over longer ranges and had almost no effect at close range. Later Types As the Swarm War developed, more advanced materials were incorporated into the basic design in order to better combat The Swarm's natural exoskeleton. The depleted uranium tip was replaced by a lightweight ballistic cap which deformed on impact, lightening the round and making it faster. The Tungsten Carbide core was replaced by a condensed CVT (Chromium Vanadium Tungsten) and Austenitic Steel alloy, which had been treated in several ways to make it stronger and more dense. This core continued travelling through the deformed ballistic cap in impact with the target, guaranteeing armour piercing. Finally, the polymer was increased in efficiency by several times, more than tripling the shield depleting power of the round and making it more effective at shorter ranges.